Weier pleaded guilty to stabbing her then-12-year-old classmate 19 times, but a jury will decide whether it was due to mental disease. If she is found guilty, prosecutors are recommending a sentence of 10 years behind bars. If she is found not guilty by reason of mental disease, she would be institutionalized for at least three years.

The jury is comprised of 12 jurors and four alternates.

Opening statements in the trial will begin on Tuesday.

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WAUKESHA, Wis. (CBS 58) – The mental health of one of two girls charged in the Slender Man stabbing case will be the focus of a trial getting underway Monday in Waukesha.

Anissa Weier has pleaded guilty to stabbing her classmate 19 times, but her lawyer argues she is not guilty by reason of mental disease. If the jury sides with her, Weier will be institutionalized until at least 2020.

If they do not, prosecutors have recommended a sentence of 10 years behind bars.

In the last hour, Anissa Weier’s attorney has taken the microphone. Maura McMahon has spoken with the jury pool about their thoughts on the case.

Weier's lawyer, Maura McMahon has taken the microphone. She is speaking to the juror pool about their thoughts on the case. #slenderman

The first potential jurors were dismissed around 10:30 Monday morning. The dozen or so dismissed had work or childcare conflicts or felt they couldn’t be impartial jurors. It’s important to note the judge ruled that jurors will be sequestered in this trial. Once the jury is selected, they will not be allowed to go home or allowed to speak with anyone about the case until the trial is over.

They will go through 100-some possible jurors each day and selecting the jury could take days.

Ultimately, the court will end up with sixteen jurors total – 12 jurors and four alternates.

Lawyers on both sides and the judge are trying to find the most impartial dozen.

The victim’s family has spoken out on Weier’s plea deal. The victim will not have to testify because of the guilty plea. They worked with the District Attorney and accepted the deal but say it’s not enough.

The state prosecutors have yet to speak with jurors. That will happen after a lunch break.

CBS 58 reporter Lindsey Branwall is at the courthouse. For updates throughout the day, follow her on Twitter, @lindseybranwall.

For more information about the case thus far, including a slideshow timeline please click here.